from small one page howto to huge articles all in one place
 

search text in:





Poll
Which filesystem do you use?






poll results

Last additions:
using iotop to find disk usage hogs

using iotop to find disk usage hogs

words:

887

views:

186346

userrating:

average rating: 1.7 (102 votes) (1=very good 6=terrible)


May 25th. 2007:
Words

486

Views

250360

why adblockers are bad


Workaround and fixes for the current Core Dump Handling vulnerability affected kernels

Workaround and fixes for the current Core Dump Handling vulnerability affected kernels

words:

161

views:

137535

userrating:

average rating: 1.4 (42 votes) (1=very good 6=terrible)


April, 26th. 2006:

Druckversion . pdf icon
You are here: System->Security

Disable uptime detection from external mashines

With the right tools you can "sniff" the uptime of a linux mashine only by sending and analysing tcp packets. The tool nmap does such a test.

Example output from nmap:

Interesting ports on 192.168.70.121:  
PORT STATE SERVICE
80/tcp open http
81/tcp closed hosts2-ns
Device type: general purpose
Running: Linux 2.4.X|2.5.X
OS details: Linux Kernel 2.4.18 - 2.5.70 (X86)
Uptime 0.667 days (since Thu Oct 21 03:21:03 2004)

This uptime statistics can be disabled by running the following command:
echo 0>/proc/sys/net/ipv4/tcp_timestamp

running nmap after that:
...  
Running: Linux 2.4.X|2.5.X
OS details: Linux Kernel 2.4.0 - 2.5.20 w/o tcp_timestamps
...

You can add that line above to you init script or modify /etc/sysctl.conf and add that line:
net.ipv4.tcp_timestamp=0


rate this article:
current rating: average rating: 1.3 (42 votes) (1=very good 6=terrible)
Your rating:
Very good (1) Good (2) ok (3) average (4) bad (5) terrible (6)

back





Support us on Content Nation
rdf newsfeed | rss newsfeed | Atom newsfeed
- Powered by LeopardCMS - Running on Gentoo -
Copyright 2004-2020 Sascha Nitsch Unternehmensberatung GmbH
Valid XHTML1.1 : Valid CSS : buttonmaker
- Level Triple-A Conformance to Web Content Accessibility Guidelines 1.0 -
- Copyright and legal notices -
Time to create this page: 36.0 ms